Introduction
The law concerning capacity to make medical treatment decisions operates under the general presumption of capacity enshrined in section 4(3) of the Guardianship and Administration Act 1990 (WA) (GA Act). This article examines the nuanced approach that must be taken when assessing capacity for specific medical treatment decisions, as distinct from the broader declarations of incapacity that may be made under the GA Act.
The Legislative Framework for Medical Treatment Decisions
Part 9B of the GA Act
Part 9B of the GA Act establishes a legislative framework for medical treatment decisions when an individual lacks capacity. This framework is critical to understanding how the law deals with specific medical decisions as distinct from broader capacity determinations.
Section 110P of the GA Act requires "full legal capacity" for a person to make an advance health directive. This represents the highest threshold for capacity under the Act, reflecting the serious and enduring nature of such directives.
For individuals who lack capacity to make treatment decisions, section 110ZD establishes a hierarchy of decision-making authority that operates outside the guardianship system. This hierarchy is as follows:
The patient's spouse or de facto partner who is living with the patient (section 110ZD(3)(a))
The patient's nearest relative who maintains a close personal relationship with the patient (section 110ZD(3)(b))
The primary provider of care and support who is not remunerated for providing that care and support (section 110ZD(3)(c))
Any other person who maintains a close personal relationship with the patient (section 110ZD(3)(d))
As noted in NJ [2025] WASAT 35 at [91], the term 'nearest relative' is defined in section 3 of the GA Act and establishes that the eldest child will be preferred if multiple children could be considered the nearest relative.
The person responsible framework in section 110ZD represents a less restrictive alternative to guardianship, allowing treatment decisions to be made without formal Tribunal intervention where appropriate. In NJ [2025] WASAT 35 at [94], the Tribunal observed that this mechanism was effective for certain medical decisions, noting that "NJ does not require a guardian to make decisions about medical treatment not covered by the AHD as KL has the authority conferred by s 110ZD."
Limitations on Medical Decision-Making Authority
Importantly, the GA Act contains specific provisions that limit decision-making authority in relation to certain medical procedures. Section 110ZJ expressly prohibits sterilization procedures unless authorized by the Tribunal under Division 3 of Part 5 of the Act. Section 3B of the GA Act specifically excludes voluntary assisted dying decisions from the scope of treatment decisions that can be made under an advance health directive or by a guardian.
These provisions highlight the legislature’s intent to ensure that particularly significant medical decisions remain subject to special procedures and safeguards, reflecting the principle articulated in Re T (Adult: Refusal of Treatment) [1993] Fam 95 that "the more serious the decision, the greater the capacity required."
The Presumption of Capacity
The starting point for any consideration of capacity is the statutory presumption that all adults possess capacity. As noted in NJ [2025] WASAT 35 at [18]:
"The starting point for the Tribunal is that every person is presumed to be capable of making their own decisions about their estate and their person. The presumption of capacity is enshrined in the GA Act as follows: (3) Every person shall be presumed to be capable of — (a) looking after [their] own health and safety; (b) making reasonable judgments in respect of matters relating to [their] person; (c) managing [their] own affairs; and (d) making reasonable judgments in respect of matters relating to [their] estate, until the contrary is proved to the satisfaction of the State Administrative Tribunal."
This statutory presumption reflects the common law position that "there is a presumption of capacity whereby an adult is presumed to have the capacity to consent to or to refuse medical treatment unless and until that presumption is rebutted" (Hunter and New England Area Health Service v A [2009] NSWSC 761 at [23], cited in NJ [2025] WASAT 35 at [47]).
Evidentiary Standards for Capacity Determinations
The Tribunal applies a heightened standard of proof when making determinations about capacity, reflecting the serious consequences of such findings. In NJ [2025] WASAT 35 at [19], the Tribunal articulated this standard:
"The presumption of capacity is a fundamental principle in the GA Act and can only be displaced by clear and cogent evidence of incapacity leading the Tribunal to be actually persuaded that the person in respect of whom the proceeding is brought is a person for whom a guardianship or an administration order can be made."
This approach reflects the principles established in Briginshaw v Briginshaw (1938) 60 CLR 336, which requires a higher degree of persuasion for findings that are serious in nature or have significant consequences for the individual. The Tribunal in NJ explicitly referenced Briginshaw in conjunction with previous Tribunal decisions in LP [2020] WASAT 25 and GC and PC [2014] WASAT 10.
The evidentiary burden for displacing the presumption of capacity has practical implications for how the Tribunal assesses evidence. As noted in NJ [2025] WASAT 35 at [20]:
"Considering the seriousness of the consequences for a proposed represented person that flow from a finding by the Tribunal of incapacity, or the consequences of the Tribunal failing to identify an incapable person in need of protection, the Tribunal must make findings of fact about capacity by reference to evidence which may be from a wide variety of sources, including the evidence of medical and allied health professionals and also lay evidence."
This approach means that the Tribunal will:
Require clear and cogent evidence of incapacity, not merely a balance of probabilities
Consider evidence from multiple sources, not just medical opinions
Be particularly careful when the finding will result in a loss of decision-making autonomy
Consider both the risk of incorrectly finding incapacity and the risk of failing to identify incapacity when it exists
The application of this evidentiary standard was demonstrated in NJ [2025] WASAT 35 when the Tribunal carefully weighed conflicting medical opinions from Dr. H and Dr. W regarding NJ's capacity to make different types of decisions. Rather than simply accepting one opinion over another, the Tribunal engaged in a detailed analysis of NJ's specific capabilities, ultimately concluding that she lacked capacity for some decisions but not necessarily for others.
Capacity as Decision-Specific Rather Than Global
A fundamental principle in assessing capacity is that capacity is decision-specific rather than global. As noted in NJ [2025] WASAT 35 at [55], when discussing the Full Tribunal's decision in C [2024] WASAT 50:
"In Guthrie v Spence [at 175], Campbell JA stated: 'It is well-accepted that there is no single test for capacity to perform legally valid acts and that the task-specific nature of these tests for capacity has the effect that the one person could have capacity to perform one task, but lack capacity to perform a different task.'"
This position is further reinforced by the observation in Hunter and New England Area Health Service v A [2009] NSWSC 761 at [24] (cited in NJ [2025] WASAT 35 at [55]):
"In this context, it is necessary to bear in mind that there is no sharp dichotomy between capacity on the one hand and want of capacity on the other. There is a scale, running from capacity at one end through reduced capacity to lack of capacity at the other. In assessing whether a person has capacity to make a decision, the sufficiency of the capacity must take into account the importance of the decision and the capacity required to make a contract to buy a cup of coffee may be present where the capacity to decide to give away one's fortune is not."
The Test for Capacity to Make Medical Treatment Decisions
The test for capacity to make medical decisions at common law has been articulated in several key decisions. In NJ [2025] WASAT 35 at [55], the Tribunal cited the Full Tribunal's summary in C [2024] WASAT 50, which restated the test from Re MB (as summarized in Hunter and New England Area Health Service v A):
"As Butler-Sloss LJ said in Re MB, in deciding whether a person has capacity to make a particular decision, the ultimate question is whether that person suffers from some impairment or disturbance of mental functioning so as to render him or her incapable of making the decision. That will occur if the person: (1) is unable to comprehend and retain the information which is material to the decision, in particular as to the consequences of the decision; or (2) is unable to use and weigh the information as part of the process of making the decision."
Similarly, in Re T (Adult: Refusal of Treatment) [1993] Fam 95 at [295] (cited in NJ [2025] WASAT 35 at [55]), Thorpe J observed that:
"the question to be decided is whether it has been established that the patient's capacity is so reduced that he does not sufficiently understand the nature, purpose and effect of the proper treatment."
Thorpe J further identified that a person needs to be able to "comprehend and retain treatment information, they need to believe that information, and they need to be able to weigh it in the balance to make a choice" (NJ [2025] WASAT 35 at [55]).
The Full Tribunal in C [2024] WASAT 50 developed a structured approach to determining capacity for specific medical decisions, summarized in NJ [2025] WASAT 35 at [55]:
"Drawing on that common law approach, we consider that in order for the Tribunal to determine whether or not [a person] is able to make reasonable judgments in respect of whether or not [a specific medical procedure] should be performed on her, it is necessary to consider: (a) What cognitive ability – that is, reasoning process – a person is required to be able to undertake in order to make a reasonable judgment of that kind; (b) What is the evidence as to [the person's] capacity in that respect; and (c) Is that evidence sufficient to displace the presumption of capacity under the GA Act to make such decisions as this one."
Notably, the Full Tribunal emphasized that sophisticated medical knowledge is not required to demonstrate capacity to make medical decisions (NJ [2025] WASAT 35 at [55]):
"At the outset, we should say that we do not consider that a person needs to be able to demonstrate a level of sophisticated medical knowledge in order to be able to make a reasonable judgment in respect of a decision such as whether to have [a medical procedure]. We think it is sufficient if they are capable of understanding the main elements of the procedure, and its risks and consequences, rather than the technical or exact details of the treatment or its effect."
Distinguished from Global Declarations of Incapacity
A critical distinction exists between capacity to make specific medical decisions and the broader declarations of incapacity that may be made under the GA Act. In NJ [2025] WASAT 35 at [50], the Tribunal noted:
"To have capacity to make this specific type of medical treatment decision, which is to choose medical assistance to end one's life, is clearly very different to a person being 'unable to make reasonable judgments in respect of matters relating to his or her person', which is the global declaration required to enliven an enduring power of guardianship. This broad mandatory declaration does not allow the Tribunal to address the specifics of a particular decision that the person is incapable of making."
This distinction is important because global declarations of incapacity can sometimes inappropriately prevent a person from making specific medical decisions they are capable of making. As evidenced in NJ [2025] WASAT 35, a declaration that a person is "unable to make reasonable judgments in respect of matters relating to his or her person" under section 110L of the GA Act prevented NJ from being assessed for voluntary assisted dying, even though such an assessment includes its own capacity evaluation.
Advance Health Directives and Capacity Requirements
The capacity required to execute an advance health directive under the GA Act is defined as "full legal capacity" (section 110P), which is not specifically defined in the Act. However, as noted in NJ [2025] WASAT 35 at [67], the Western Australian Department of Health provides guidance that "full legal capacity" in this context means the person:
"• understands any information or advice given to you to help make decisions in your Advance Health Directive • understands the likely effect(s) of the decisions you make in your Advance Health Directive on your future treatment and care • are able to weigh up the possible pros and cons of your decisions about your future treatment and care • are able to communicate your decisions about your future treatment and health care in some way."
The Tribunal in NJ [2025] WASAT 35 at [68] observed that these requirements closely parallel the decision-making capacity requirements for voluntary assisted dying under section 6(2) of the Voluntary Assisted Dying Act 2019 (WA).
Balancing Protection with Autonomy
The Tribunal's approach in cases like C [2024] WASAT 50 (described in NJ [2025] WASAT 35 at [51]-[55]) demonstrates the careful balance required between protecting vulnerable individuals and respecting personal autonomy in medical decision-making. In that case, despite having a guardian appointed with authority to make medical treatment decisions, Ms AB was found capable of making a reasonable judgment about whether to have an abortion.
Similarly, in NJ [2025] WASAT 35, the Tribunal revoked a declaration of incapacity to make reasonable judgments in respect of matters relating to the person, which allowed NJ to be assessed for capacity to make decisions about voluntary assisted dying. This approach recognized that capacity is decision-specific and that a person may retain capacity to make certain medical decisions even if they require assistance with other aspects of their personal affairs.
Worked Example: Assessing Capacity for a Specific Medical Decision
Case Study: Mrs. Wilson
Mrs. Wilson is a 72-year-old woman diagnosed with early-stage dementia. She resides in an aged care facility and has a limited guardian appointed by the Tribunal who makes decisions about her accommodation and services, but not for medical treatment decisions. The Tribunal previously made a declaration that she was "unable to make reasonable judgments in respect of matters relating to where she should live and what services she should access." Mrs. Wilson requires surgery for cataracts that will significantly improve her vision. The surgeon has requested an assessment of Mrs. Wilson's capacity to consent to this procedure.
Application of Principles
Step 1: Consider the presumption of capacity
The absence of a limited guardian appointed specifically for medical treatment decisions is significant in this case because section 4(3) of the GA Act establishes a presumption of capacity that applies to specific decisions not covered by existing guardianship orders. The limited nature of the guardian's authority and the specificity of the earlier declaration of incapacity (relating only to accommodation and services) means that the presumption of capacity remains intact for medical decisions like the proposed cataract surgery (consistent with the approach in NJ [2025] WASAT 35 at [50]).
Step 2: Assess capacity specifically for the cataract surgery decision
Following the approach in C [2024] WASAT 50 (as cited in NJ [2025] WASAT 35 at [55]), the assessment considers:
(a) What cognitive ability Mrs. Wilson requires to make this specific decision; (b) The evidence of Mrs. Wilson's capacity in respect of this decision; and (c) Whether that evidence displaces the presumption of capacity.
During the assessment, Mrs. Wilson demonstrates that she:
Can explain that the surgery will "fix her cloudy eyes" and help her see better
Understands the procedure involves removing her natural lens and replacing it with an artificial one
Comprehends that there are risks of infection and bleeding, though cannot recall all the technical details
Recognizes that without surgery her vision will continue to deteriorate
Expresses a consistent preference for having the surgery to improve her quality of life
Can communicate her decision and reasoning clearly
Step 3: Apply the legal test for capacity
Applying the test articulated in Re MB (cited in NJ [2025] WASAT 35 at [55]), Mrs. Wilson:
Can comprehend and retain the material information about the cataract surgery
Can use and weigh that information in the decision-making process
Can communicate her decision
Step 4: Determine if Mrs. Wilson has capacity for this specific decision
The assessment concludes that Mrs. Wilson has capacity to make this specific medical decision regarding cataract surgery, despite having previously been declared unable to make reasonable judgments about accommodation and services. Consistent with NJ [2025] WASAT 35 at [50], her capacity for this specific medical decision is distinguished from her difficulties with decisions about where she should live and what services she should access. This demonstrates the decision-specific nature of capacity assessments and reflects the Tribunal's approach of avoiding overly broad declarations of incapacity that might unnecessarily restrict autonomy in areas where capacity remains intact.
Checklist for Assessing Capacity for Specific Medical Decisions
Preliminary Considerations
☐ Review existing orders and declarations regarding capacity (guardianship orders, administration orders, declarations under s.110L)
☐ Identify the specific medical decision requiring assessment
☐ Consider the complexity and gravity of the decision (following Lord Donaldson's principle in Re T (Adult: Refusal of Treatment) [1993] Fam 95)
☐ Begin with the presumption of capacity regardless of any existing orders
Assessment Process
☐ Provide information about the medical decision in clear, simple language
☐ Assess the person's ability to understand the information provided
☐ Determine if the person can retain the information long enough to make a decision
☐ Evaluate whether the person can weigh the benefits and risks
☐ Confirm the person can communicate their decision
☐ Consider whether any impairment or disturbance of mental functioning affects:
☐ Comprehension of information material to the decision
☐ Retention of that information
☐ Use or weighing of that information in the decision process
☐ Communication of the decision
Documentation Requirements
☐ Record the specific medical decision being assessed
☐ Document the information provided to the person
☐ Note the questions asked and responses given
☐ Detail observations of the person's understanding and reasoning
☐ Specify the date, time, and environment of the assessment
☐ Document any fluctuations in capacity observed
☐ Record the conclusion regarding capacity for this specific decision
☐ Provide reasoning that references the applicable legal tests
Next Steps
If the person HAS capacity for the specific medical decision: ☐ Respect their decision even if it contradicts a guardian's view
☐ Document the finding of capacity
☐ Proceed according to the person's decision
☐ Consider whether a review of existing guardianship orders is warranted
If the person LACKS capacity for the specific medical decision: ☐ Determine the appropriate substitute decision-maker:
☐ Enduring Guardian pursuant to an Enduring Power of Guardianship (if applicable and specifies appropriate functions)
☐ Person responsible under s.110ZD of the GA Act
☐ Consider whether a guardianship application is required
☐ Document the finding of incapacity and the basis for this conclusion
☐ Ensure the substitute decision-maker has sufficient information to make the decision
This checklist reflects the principles established in NJ [2025] WASAT 35 and the cases cited therein, particularly the emphasis on decision-specific capacity assessments rather than global determinations of capacity.
Conclusion
The assessment of capacity to make specific medical treatment decisions requires a nuanced, decision-specific approach rather than global determinations of capacity. As demonstrated in NJ [2025] WASAT 35, the Tribunal must carefully consider whether a person has the cognitive ability to understand, retain, and weigh information relevant to a particular medical decision, rather than applying broader findings about capacity to all types of decisions. This approach ensures that individuals retain autonomy over medical decisions they are capable of making, even if they require assistance with other aspects of their personal or financial affairs.
The Tribunal's approach in these cases reflects the fundamental principle articulated by Lord Donaldson in Re T (Adult: Refusal of Treatment) [1993] Fam 95 (cited in NJ [2025] WASAT 35 at [42]): "the more serious the decision, the greater the capacity required." This principle guides the assessment of capacity for specific medical decisions, ensuring that the standard of capacity required is proportionate to the gravity of the decision at hand.